CXCR6 and neoplasm: The proportion of tumor-infiltrating CXCR3+ NK cells was lower in patients with LN metastasis than in those without, indicating the importance of CXCR3+ in tumor development.199 In the early study, irradiation enhanced the expression of CXCL16 in breast cancer cells and increased the migration of activated NK cells expressing CXCR6 into breast cancer tissue, thus enhancing the NK cells’ anti-tumor function.201